Display & indicator lights, The 662 display & indicator lights – tekmar 662 Snow Detector & Melting Control User Manual

Page 8

• Outdoor temperature is the temperature measured by the Outdoor Sensor 070.

• Slab Surface temperature is the temperature of the slab surface as measured by the Snow/Ice Sensor 090. If a Slab Sensor 072

is used, the control provides a best guess for the slab surface temperature when the sensor is placed 1" below the surface.

• System Supply temperature is the temperature of the water/glycol solution entering the slab. This temperature may be limited by

the control to protect the snow melting system components (see Settings - Max. Supply).

• Actual

∆

T is the difference between the system supply and return temperatures which gives an indication of the present heat output

to the melt system. The Actual

∆T may be limited by the control to protect the slab (see Settings - ∆T Max).

• Target

∆

T is the

∆T (heat output) that the control is trying to achieve. If the Actual ∆T is below the Target ∆T, the control is trying to

increase the heat to the slab. The Actual

∆T may never reach the Target ∆T because the system supply or boiler return temperatures

may be limited (see Settings -Max. Supply, Min. Boil. Return).

• Boiler Return Temperature is the temperature of the fluid entering the boiler. This sensor reading may cause the control to limit the

heat output to the slab in order to protect the boiler (see Settings - Max Boil. Return).

• Relative Energy Usage (

∆T x hours). This display allows the user to estimate the amount of energy used by the snow melt system.

The relative energy usage is displayed by alternating between two numbers. When the

°C or °F segment is off, the thousands are

display . When the

°C or °F segment is on, the units are displayed . The energy consumption can be estimated by multiplying the

∆T x hrs by the system flow rate (in US GPM) and by the constant K given in the adjacent table. The accumulated energy usage
information can be cleared while the control is in the energy usage display. To do this, press and hold the item button for 1 second
and then press the test button.

Example -

∆T x hrs = 005 (thousands) 225 (units) = 5225 °F x hours
System flow = 20 US GPM
Fluid = 40% glycol & 60% water, therefore K = 462
Energy Usage = 5225 x 20 x 462 = 48,279,000 BTU

• % Output - If a variable speed pump is used, this display indicates the percentage of maximum flow through the pump. If the pump

flow rate is 50% of maximum flow, the % Output is 50%. If floating valve action is used, this display indicates the percentage the valve
is open. If the valve is half open, the % Output is 50%. If a 4-20 mA device is used, this display indicates the percentage of current
output (between 4 and 20 mA) supplied to the device. If the % Output is 50%, the control is delivering 12 mA to the device.

Motor Speed/ Pump Response (con't)

Motor Speed (mixing valve and 4-20 mA outputs)

- When operating a valve, the control uses the information from the “Motor

Speed” dial setting to synchronize various control actions to the valve position and its rate of change. Set this adjustment to match
the time required for the actuating motor to drive from the fully closed to the fully open position.

The 662 Display & Indicator Lights

K values are calcu-
lated averages for
most ethylene glycol
solutions at 50

°F

(10

°C). K increases

with higher tempera-
tures.

°F °C

OUTSIDE

After power-up,

the control

shows the

"OUTSIDE"

temperature

Item

POWER-UP DISPLAY

OUTDOOR TEMPERATURE

SLAB SURFACE TEMP.

SYSTEM SUPPLY TEMP.

ACTUAL

∆T

TARGET

∆T

BOILER RETURN TEMP.

ENERGY USAGE

% HEAT OUTPUT

Slab
Supply
Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab

Supply
Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab

Supply
Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab
Supply
Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab
Supply
Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab
Supply
Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab
Supply
Actual

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab

Supply

Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

Slab
Supply

Actual

∆T

Target

∆T

% Output

Usage (

∆T x hrs)

Boiler Return

°F

OUTSIDE

°F

Press and

release the

item button

Item

Press and

release the

item button

Item

Press and

release the

item button

Item

Press and

release the

item button

Item

Press and

release the

item button

Item

Press and

release the

item button

Press and

release the item

button to scroll

through the

displays again

Item

Press and hold the item

button for at least 1

second to switch

between

°F and °C

Target

∆T

°F

Item

Press and

release the

item button

% Glycol by

weight

10%
20%
30%
40%
50%

Freezing

point

-13

-35

@ 50

500
496
487
477
462
439